A good hot water supply improves milk quality!
Having an adequate and reliable supply of hot water is essential in the production of high quality milk.
Hot water is necessary for the cleaning of milking machines and pipelines, receivers and bulk milk storage tanks. Hot water must be available in adequate quantities and at the required temperatures for each cycle in the cleaning process.
Failure to have adequate supplies of hot water at suitable temperatures can lead to rapid increases in bacterial contamination and subsequent reduction in milk quality. Milk quality reductions can lead to a loss of quality premiums or, in the worst case, a refusal to accept the contaminated milk at the processing plant.
Hot water requirements vary from farm to farm and are dependant on the number of cows, number of milking units, pipeline sizes and lengths, and system layout (receivers, plate coolers etc.). Generally, a minimum hot water requirement is about 15 litres of 70ºC water per milking unit for each rinse/wash/rinse cycle.
Water temperatures required for various milking equipment rinsing, washing, and sanitising cycles are as follows:
Pre-rinse cycle 35ºC - 45ºC
Wash cycle 65ºC - 75ºC
Acid rinse cycle 35ºC - 45ºC
Sanitise cycle 25ºC
Electric Water Heating is Expensive
Solar – Free Energy from the Sun
Solar heating can save the farmer money. Solar energy is free and can make a substantial contribution to water heating in the summer months when hot water usage is at its peak. It can be supplemented by electricity when sunshine levels are not sufficient to heat all of the water needed.
It is good for the environment too!
Solar heating reduces emissions of CO2. Solar heating is environmentally friendly because it replaces the use of fossil fuels such as oil, coal and gas, which are used to generate electricity.
How doest it work?
The principle of operation is simple. The solar collector is supplied complete with a mounting frame as shown in the picture below. The frame must be mounted so that it is firmly secured to a flat surface. The mounting must be secure enough to support the weight of the unit and resist the force of the wind.
The solar energy collector must be mounted so that it faces south. The collector is fitted with specially designed vacuum tubes. These allow sunlight in but do not allow heat out. The tubes contain water, which is heated by the solar energy. This water rises as it is heated and gradually fills the tank with hot water. The tank temperature can rise as high as 90ºC on sunny days.
The tank contains a copper heat exchanger coil. One end of the coil is connected to the cold water supply and the hot water outlet at the other end. The water is heated as it passes through the heat exchanger coil. This water is used for washing and sterilising the milking equipment.
The water contained in the solar tubes and tank is never mixed with the hot water produced by the system. This means that hot water used for cleaning is never stored and there is no risk of legionella growth or other contamination, which may be a problem with other types of water heater. This is a big advantage, which ensures the highest level of hygiene.
Electric Immersion Heater for when the Sun does not shine
The solar water heater is also fitted with an electric immersion heater. This has an inbuilt thermostat, which comes on automatically when the tank temperature is below 60ºC and turns off when it reaches 85ºC.
The water heater is supplied complete with a mounting frame, which is mounted on a flat surface like a concrete base, flat roof or a bracket.
The solar water heater is installed so that the collector faces due south, if possible. It will work at any orientation between South/East and South/West, although its output will be reduced.
The solar water heater is rigidly mounted so that it can withstand strong winds to which it may be exposed. If it is mounted on a supporting structure such as a roof frame, the strength of the supporting structure should be carefully checked to ensure that it can support the weight of the solar water heater and the water which it contains. Remember that 1 litre of water weighs 1kg. The total weight of the solar water heater, when it is full of water is approximately 400kg.
Solar Water Heating System installed on roof of Dairy farm near Castlemahon, Co. Limerick, Ireland
A supply of clean water at a reasonable pressure must be available. A minimum pressure of at least 1 bar (10m head) is recommended. In order for the water heater to work well, it should be supplied from a pumped or mains cold water supply.
The water heater is well insulated and is protected from freezing in winter by its vacuum tubes and electric heater. It is important to ensure that the pipes connected to the water heater are insulated and protected from frost. All pipes should be fitted with trace heating tape.
Stainless Steel tank – 240 Litre capacity with 50mm insulation;
24 x Vacuum Tubes 1800mm long;
Painted galvanised steel frame with stainless steel fasteners;
Contains 1.5 kW Immersion heater with inbuilt thermostat. ON60ºC / OFF80ºC
May be connected to an additional heat source such as a boiler if desired.
Weight (empty): 144kg
Weight (full): 388kg
Water connections: ½” BSP
Mounting angle: 45º
Solar Aperture Area: 2.6m2